Consumers can interact with merchants to conduct various financial payment transactions. For example, a consumer can conduct a transaction with a merchant at a point-of-sale system using cash, a transaction card, or other transaction instrument. Conventional systems can include expensive and bulky financial transaction electronics, as may include a card reader for payment cards (e.g., debit or credit cards), a cash drawer, monitors, keyboards, and various other electronic devices. Oftentimes, however, this equipment can be costly and large, requiring additional space and resources. Further, in retail stores where space is limited, a merchant may not require all components that come with conventional point-of-sale system or at least may find it desirable to piece together a modular or mobile system to streamline the checkout experience. Further still, merchants may find approaches to conducting a financial transaction using conventional systems burdensome, where during a transaction, if a customer pays by credit card, the merchant has to enter a transaction amount and the merchant or the customer has to swipe the credit card in the card reader. Further, many transactions require that the customer sign a physical receipt, electronically approve a transaction, e.g., by pressing an approve button on a user interface, electronically sign for the transaction, e.g., with a stylus or finger on an electronic signature capture device with a touch sensitive pad, or enter an authorizing personal identification number (PIN), many of which techniques require additional financial transaction electronics and time. Some point-of-sale systems require multiple types of card readers and/or complex and bulky card-reading equipment in order to accept multiple types of payment cards.